1. Technical Field
This invention relates generally to static gaskets of the type used to establish a gas/fluid-tight seal between two members to be clamped together, and more particularly to exhaust manifold gaskets.
2. Related Art
In establishing a gas/fluid-tight seal between two members to be clamped together, such as between cylinder block and engine block or an exhaust manifold and engine block, it is common to use a static gasket having a single layer of a single piece of material, or a plurality of stacked layers overlying one another formed as a multilayer gasket. Generally, at least one of the layers of the multilayer gasket, sometimes referred to as a functional layer, has a seal bead to facilitate establishing a gas/fluid tight seal about an opening. The functional layer needs to be fabricated of a material suitable for establishing and maintaining the gas/fluid tight seal, and further, typically needs to be able to withstand high temperature environments. As such, the functional layer material needs to constructed from a high quality metal, typically coming at a relatively high cost. As such, use of the high cost functional layer material increases the overall cost of the gasket, and in addition, typically results in high cost waste material.
In addition, to minimized the possibility of over compressing the seal bead of the functional layer, a stopper layer in a multilayer gasket needs to be constructed of a predetermined thickness material to ensure the bead or beads remain functional. Unfortunately, metal sheet material typically used as stopper layer material is produced having a generally wide thickness tolerance, such as about +/−0.001″, and thus, it can be difficult to tightly control the stopper height, wherein the stopper height is provided by the material thickness. As such, to avoid over compression of the seal bead in the functional layer, the manufacturer typically errors on the side of having a thicker stopper layer than may be necessary in order to account for inherent manufacturing tolerance fluctuations. Unfortunately, this also adds cost to the gasket assembly.